Because part of the interior of the white mulberry, upon which silkworms thrive best, is composed of a tissue of beautiful white silky fibres, much resembling China silk: hence, the basis of the material, in its proximate form, is derived from the vegetable kingdom, though the spinning of its substance into a lengthened thread, is entirely due to the mechanical functions of the silk-worm.
The growth of the silkworm has been tried, but with no great success, in this country. Evelyn computed that one mulbery-tree would feed as many silkworms annually as would produce seven pounds of silk. "According to that estimate," says Barham, (dated 1719,) " the two thousand trees already planted in Chelsea Park, (which take up one-third of it) will make 14,000lb. weight of silk; to be commonly worth twenty-shillings a-pound, those trees must make £14,000 per annum."
Because the leaves are supposed to be more nutritive ; but, in that case, the silk produced is not so delicate and fine.
Of the kind and size of the silkworm also is the Sustillo, a caterpillar bred in the pacae, a tree well known in Peru. When completely satiated with the leaves, it spins a fine silk paper, which has been gathered measuring a yard and a half in length. In proportion to the vigour and majestic growth of this tree is the number of insects it nourishes.
Because the labour in preparing new silk affords much more employment to the country producing it, than any other raw material. The fact has been established before a Committee of both Houses of Parliament. We may add, that the raw silk imported into England, from all parts of the world, in 1814, amounted to one million six hundred and thirty-four thousand, five hundred and one ponnds; and in 1824, to three millions, three hundred and eighty-two thousand, three hundred and fifty-seven. The official values of these imports are £703,009, and £1,464,994.
Because the insects that produced it were indigenous to those countries. It was thence brought to Europe in small quantities, and m early times sold at so extravagant a price, that it was deemed too expensive even for royalty.
Because they considered silk unclean, from its being produced by a worm. Hence it was decided that a person wearing a garment made entirely of silk, could not lawfully offer up the daily prayers enjoined by the Koran. - Herbelot.
The history and economy of the silkworm would occupy some score pages, but these few facts are the latest illustrations.
Because they may there survive the winter, and be hatched in spring ; the living principle, though not in a state of activity, being capable, as it would appear, of withstanding severe cold.
Because they may be always ready to drop down in safety, by extending this thread, on the sudden approach of their enemies.